Emergence of tight oil and shale oil offer abundant oil resources. However, it poses significant processing challenges due to the difference in oil properties and chemical compositions. Specifically, in order to process tight/shale oil using FCC technology in a refinery, one big challenge is the high levels of unconventional metals, such as iron and calcium, as compared to processing conventional crude oil.
High levels of iron, calcium and other metals, for example, may result in deposition of iron and calcium on the catalyst surface. The deposited iron and calcium may form a thick layer of metal shell on the catalyst, causing a loss of diffusivity of oil vapor. This results in a loss of conversion and an increase in coke and heavy oil products. A high level of iron and calcium deposition on catalysts may change the catalyst properties, affecting catalyst circulation and leading to processing and performance issues.
In order to minimize the effect of these unconventional metals, especially at higher contaminant levels found in tight/shale oil, refiners usually must significantly increase their daily catalyst addition to mitigate metal deposition on catalyst and facilitate catalyst circulation. This, however, leads to a dramatic increase in operation cost.
Various methods and additives have been proposed to remove metals from catalysts. The additives have been proposed for use as a diluent in a riser reactor, for example, or contacted with a catalyst in a catalyst cooler, as another example. Patents related to such processes and additives include U.S. Pat. Nos. 8,197,669, 6,610,255, 5,286,691, 5,260,240, 5,174,890, and 4,465,588, among others.